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Why would a local network go down when a local server is powered down?

tr flag
Max

I'm running Ubuntu 20.04 on a machine hosting various websites, an email server, and a bind9 DNS server. Whenever that machine is powered off, the network connected to a local network Linksys router goes down.

  1. Internet connected to provider modem
  2. Modem connected to provider router
  3. Provider router connected to Linksys router
  4. Linksys router manages local network

The router has a dedicated IP address and handles port forwarding to the local machine The DNS servers listed on the router are those provided by the internet provider A tracert from a device on the local network traces trough the local Linksys router, then the providers router then to the internet and does not reflect the IP address (neither the local, nor external server address).

What should I be looking at first to find out what may be causing this issue?

cn flag
What do you mean by "Linksys router goes down"? Is it powering off? Is the Wifi radio off? DNS issues? What about traceroute to `8.8.8.8` (Google DNS): is it passing trough the routers. How is the output of traceroute different when you have the issue compared to when everything works fine? Maybe it's a DNS issue?
tr flag
Max
I mean the local network loses internet through the Linksys router. This affects both wifi and wired devices on the network. The tracert I performed was to google.com. The first response is the Linksys routers ip address (192.168.1.1) then the providers router ip address, then out of the network to the internet through normal hops. I assume it's a DNS issue, but I can't find anything on the local network that points to the local machine address as the DNS provider. Those in the BIND zone configs point to the external IP address of the server.
in flag
If tracery works then you don't have internet issues, but you do mention DNS, maybe start there. What config does the router have?
another victim of the mouse avatar
cf flag
If you're running bind on the Ubuntu Box as a DNS provider that is forwarding requests upstream to ISP than it's likely that when the machine is powered off DNS requests are dying. Where are your machines getting their network DHCP info? Is DHCP server giving out DNS address of the Ubuntu that is powered off? Can you use the ping commands while the Ubuntu server is off? Do IP address route and resolve correctly?
tr flag
Max
@NiKiZe, I'm going with the assumption it's a DNS issue as well, but I just don't see anything on the router that points to my server as the DNS server for the network.
cn flag
Which DNS server is used by you local machines? Is it the Linksys router, the Ubuntu server or an external DNS?
tr flag
Max
The Linksys router provides the DNS information to the network.
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